1. Field of the Invention
The invention relates generally to mixing and dispensing sprayers and more particularly to aspiration type sprayer for use in dispensing small quantities of a liquid based chemical into a relatively large quantity of a carrier fluid.
2. Description of Related Art
Every year thousands of gallons of chemicals such as fertilizers or pesticides are applied to crops, plants, lawns, flowers, vegetable gardens and other organic type vegetation. Such chemicals are sold to the consumer in concentrated form and therefore are extremely hazardous to the consumer end user and environment in general. Accordingly, these hazardous chemicals preferably are marketed in containers with a sprayer head permanently attached thereto so as to minimize accidental exposure to the consumer, such as from careless handling. Furthermore, a tamper proof container arrangement is needed to prevent unauthorized access by children whose curiosity sometimes gets the better of them. To make such nonrefillable products economically feasible, it is necessary to provide a sprayer which is of sufficiently low cost to allow the bottle and sprayer arrangement to be discarded when the container contents have been all used up. In order to be commercially accepted such a sprayer must be inexpensive to manufacture and yet operate reliably and safely provide a desired mixing ratio to meet the particular requirements of the individual user.
Several aspiration type sprayers have evolved over the hears, but have met with certain disadvantages that make them undesirable. For example, U.S. Pat. No. 4,750,674 issued to Chow et al., discloses a sprayer having a system of air vent and aspiration openings of different sizes to obtain a selection of discrete mixing ratios. The mechanism requires a system of cups to block openings associated with nonselected aspiration rates and to provide the desired fluid communication. Such a system, however, requires the alignment and assembly of a plurality of elements including openings, cup seal and springs. Such a system is complicated to manufacture and assemble and therefore is undesirably expensive. Further, such devices fail to provide a simplified sprayer with a minimum of parts that are of simple design to promote reliability.
Other conventional sprayers, such as that described in U.S. Pat. No. 3,186,643 issued to George et al. use a rotating carrier fluid valve having a range of adjustability of carrier fluid flow in combination with a vent bore closure boss extending from the rotating valve. George et al's. sprayer arrangement, however, like other conventional sprayers disadvantageously has many parts which makes it an undesirable alternative for a low cost disposable type sprayer.
An improved aspiration-type sprayer is disclosed in a co-pending patent application Ser. No. 468,845, filed Jan. 23, 1990 now U.S. Pat. No. 5,039,016 for Aspiration-Type Chemical Sprayer also assigned to the assignee of the present invention which includes a sprayer head assembly sealingly mounted onto a container for storing a chemical to be dispensed. The sprayer head includes a multi-function unitary valve providing an aspiration opening simultaneously with full communication of the container interior to atmospheric pressure. The valve may include means for positive and simultaneous closure of the aspiration and vent passages so as to seal the chemical in the container when the sprayer is not in use. The sprayer assembly is coupled to a source of pressurized carrier fluid such as a garden hose. The carrier fluid is controlled by a control valve which blocks the flow of water from the hose when the sprayer is not in use. While this sprayer is of simple construction, two valves typically are employed. It would be an advancement to the art to have a sprayer arrangement that includes only one valve to control aspiration, venting and carrier fluid flow in a simple yet reliable construction.